How to find the ideal brushed motor for your rock crawler || Holmes Hobbies || Motor design

[@crxpablos]

Holmes talkin Ohms

[@FerociousSniper]

There's so much you need to know if you're gonna start undgrading the electronics. I always learn something new when I research it.

[@RadonManRC]

Great video. Very interesting to see the science behind our hobby.

[@HolmesHobbies]

More to come!

[@mishmasta]

I'd love to see a follow up to this video with the static torque test you talked about, and a nice concise conclusion to wrap it up. I think it could help clear up a lot of misconceptions about torque and brushed motors (e.g. higher turn = higher torque).

[@RenoLaringo]

So refreshing to listen to someone so passionate about his job! Motors are enigmous. They harvest living energies, both electrical and magnetic. There sure is A LOT to know and learn about how to make them the best. Really awesome vidéo, thank you ! Greetings from Belgium👍

[@HolmesHobbies]

Well said!

[@rc7178]

Good morning, math.

[@roblow8126]

awesome, loved it. great to get an insight into your mind

[@HolmesHobbies]

Glad you enjoyed it!

[@Oper8or]

I really like this video. It helps me better understand what I need for some of my rigs. This series has been a wonder to watch.

[@calebgrefe8922]

This was tremendously well explained! Thank you!

[@HolmesHobbies]

Glad you enjoyed it!

[@thercvanman2730]

Dropping that knowledge like a modern day Mr wizard. 🤙🤙🤙 Always enjoy the technical info.

[@rcmakingtracks18]

Ha, excellent. I think I'll stick with your 35 turn recommend for now, but great info. Thanks for sharing.

[@jeffgTrialsBikes]

So interesting! Thank You

[@HolmesHobbies]

Glad it was helpful!

[@mr.dizzzm7385]

great explanation, thx a lot man

[@CasperRc81]

Bottom line with a brushed motor buy a Holmes and always buy 5slot for crawling. Pinion down I like to go as small as possible. If have the room run a 550 can the torque is considerably noticeable. -I just put a sealed can with bearing at the shaft. A HH 550 can sport 45t 5slot into my traxxas hauler. It’s half the speed at least in 1st and 2nd gear. I load the bed and tow my 4ws Capra on a trailer. It’s incredibly powerful. Thank you for your engineering it’s very appreciated. -ps I’m hooked on the HW 2in1 pro and SE motors tho sorry. It fixes axials pos internal hi gearing on the scx10iii early bronco and my 4ws Capra both running an 11t pinion 😊

[@saturnfivehynrgrc581]

Good info Mr. H

[@ridgerc5976]

This was a very great explanation of info. I was lost halfway through, so I guess that green leafy weed did melt some brain cells over the years. Lol. All i know is my BRXL with the 16t Crawlmaster Expert works awesome and my Mamba Micro with your Puller Pro Stubby 2200kv is amazing and the other two rigs running your 13t Crawlmaster Expert motors never let me down. I've got a Capra project in the works so I'm thinking the BR Mini with a Crawlmaster Pro 13t is what it needs. Thanks and keep up the great work.

[@smashtj666]

Well......if that was a bullet.....im safe....it missed me by a mile...lol.... Thanks for the content John....

[@beleg1437]

Cool video! You should get together with Ryan from 'RC Explained' for some colab videos. He has put together a motor test rig. Your channel and his have been my goto source for learning about RC electronics since getting into this hobby a few years ago. Thanks for all the great information.

[@HolmesHobbies]

That would be cool!

[@georgespiggot8502]

When I used to race back in the 90's I used a Trinity 12 Turn Triple in my Tamiya Egress. Gearing would change from 13:1 to 10:1 depending on the track. The only thing we worried about was the battery not going flat by the end of the race. Timed 4 minutes. As batteries got bigger the number of turns dropped. Bigger I mean 2000mah from 1700mah. Lower turns was always better if could gear appropriately for battery to last the race. There were different classes, Modified which was any motor you wanted, then Stock for 27T motors. They were meant for beginners. Couldn't actually lower the gear ratio as much on the 27T as didn't have the acceleration out of the corner if did due to lack of torque. 27T usually also had specifications on amount of timing on the motor. Some races required non adjustable end bells for set timing. So people started to cut half the brush off to increase the timing. A few degrees extra timing was way more important than the extra brush contact area. Those brushes were almost throw away items. Super soft as well as small contact/wear area. What was meant to be a cheap category for beginners yet became one of the most expensive. For crawlers I think all the same things apply. Gear as best as can, then lowest number of turns. Rather than worrying about the battery lasting 4 minutes, now it is about things overheating. As long as engine and ECU are aren't getting too hot then try a few turns lower. The added benefit of the lower resistance of the lower turns is better braking torque also. Single turn motors for crawlers as that give the most torque at the bottom of the rev range. Offroad racing was double and triples. Onroad triples and quads.

[@HolmesHobbies]

There is a limit with crawlers, in that we can't go too low of turn or the brushes saturate in a bind and the motor just produces heat. 27t is really the fastest. 30t is about golden zone, and 35t is where torque density starts to drop off on any certain voltage.

[@georgespiggot8502]

Is there an issue with going to even lower gearing? If at 60:1 with a 30T, why not 120:1 with a 15T? 90:1 with 21T... Are the crawlers limited in gear ratio or is there another reason?

[@HolmesHobbies]

@georgespiggot8502 there is limitations to gearing but the brushes are the main choke point. Twice as fast means twice the amps for the same torque output. And heat is square of amps. The 15t generates 4x more heat in the brushes (and phase side mosfets) as the 30t for any torque output. Even with twice the gear down, the brushes would still see twice the heat with a 15t as 30t and turn into a thermal runaway without very careful setup and use.

[@georgespiggot8502]

​@@HolmesHobbies Thanks. That is exactly what I wasn't sure of. Half turns is 4x heat, halved by gearing so still double the heat overall. Do brushless motors fix the issue of overheating when in a stalled position, or do they just overheat in a different way?

[@HolmesHobbies]

@georgespiggot8502 brushless motors don't overheat nearly as much, so the roughly 2100kv limit of brushed becomes about 3500kv limit brushless. This is all assuming 36mm motor diameter. Brushless creates heat and voltage drop in the phase wires and esc still though, so as we get above 2700kv the torque delivery still gets soft. above 3500kv becomes a potential for thermal runaway and poor feeling throttle.

[@SwampersRC]

I'm on a fixed income which doesn't allow much of a hobby budget, so I tend to go for cheap electronics. I DO subscribe to the gear-down volt-up theory but because of the budget restraints even though I use a 4s ESC I only run 3s batteries. I would love to see the static torque test you mentioned, I think it would be very interesting!

[@s1lentcalib3r]

What motor do you recomend for the traxxas summit that camewith a titan 775 10 turn.

[@davethrelkeld7060]

Great video. I would love to see more like this. I enjoy math and really like the practical application of formulas, especially when we can use them to better understand electrical theory. Do you have any suggestions for reading to get a better grasp on saturation?

[@morris4069]

Nothing wrong with a budget build! I don’t understand the ultra scale bodies that either cost $150 or took 100’s of hours to finish when it takes one roll down a hill climb to destroy it! Don’t even like the price of bodies now a days! A simple looks like a truck with a simple paint job cause it’s going to get destroyed is good enough for me. I get the kit and give it a simple paint job. I’m an old touring car racer so it’s the body of the month with a light coat of paint n maybe a backing coat of white and run it! It’s going to last the season maybe with the help of drywall mesh n shoo goo but that’s about it, it won’t look pretty! It’s a hobby, have fun!!

[@jonlaird5082]

My brain just saw a bunch of numbers and just fried,lol. But you made me kinda understand a little. But I am curious what you would recommend for me and my rig. I'd like to stick to brushed as it's always what I used. I never tried brushless but wouldn't mind trying 1. I'm currently running your torquemaster br-xl esc as I used them for a number of years with great luck. My old cheap 550 motor died so I need a better motor. I could care less about speed as my rig is a 2 speed. I would like to have good torque. I was curious what you would recommend? Not sure if it matters but my rig ain't no light weight as it's pushing near 18 lbs,lol. I mainly run 2s but on rare occasions I run 3s. Thanks

[@FatherDaughterRC]

Wow! That is a tank of a rig. I'd be curious to see that in action. I'm sure it's very realistic!

[@rekik66]

Looking forward to your test. Would this info translate to the 1/24 motors?

[@whitsrcleftovers2707]

Torquemaster pro 550 21t on 3s good for the hauler? 9/45 gearing and the two speed gearbox.

[@NOSfusion]

You should really consider doing a deep dive on brushless motors regarding current backflow when changing gears. E.g., switching from low to high on a standard Traxxas radio. I believe this is what’s causes a brushless system to fail, “melt” as everyone on the forums talks about. A brushed system obviously doesn’t have this issue. Would be a great comparison piece.

[@sergeantmtb]

Why is your Crawl Master 18T if ~35 is more ideal? Great video, a little over my head but enjoyed it

[@HolmesHobbies]

The turn counts are chosen for max wire fill (cmils) on available wire guages. 5 slot crawlmaster and 3 slot torquemaster have different armatures so the natural wind count and kv will differ for each wire gauge

[@RemedyTalon]

Yes, we need to kill the myth that a slower, higher turn motor always produces more torque. I see this all the time on the forums and facebook pages.

[@HolmesHobbies]

absolutely, I know it can get a little confusing sometimes, the details do make a difference

[@moreno8903]

So would your CrawlMaster Ssport 13T 540 brushed would be good for a trx4 sport?

[@HolmesHobbies]

13t550 imo

[@micheltetreault2979]

I probably have a way find out what is the torque capacity I will work on it and have it to you if needed ✌️

[@piercetheheavens]

I'm crawling with a crawlmaster sport 10t with a stock traxxas xl5hv. Somehow it's still alive after all this time.

[@billcox87]

what the hell did you just say to me lol!!!!!!!! understood some but not all, but loved every word! Nothin like hearing the thoughts of a mad fucked up scientist;) i have and tried just about all HH brushed motors and by far , the 10T and 12T crawlmaster pro 550 are my absolute favorite motors of all, call me old school but still like the feel of a good brushed motor, don't get me wrong, i have many rigs with puller pro's but still just something about the brushed motor's that still pull me. stay groovy ...and fucked up brotha!!!

[@jerryvolpini7987]

Huh?! (I'm just going to take your word for it 🤪)

[@Organized-_-Chaos]

dam this guys hardcore using graph paper to write nots and not having crazy problems reading what he wrote

[@HolmesHobbies]

absolutely

[@mikehuber861]

Anyone know what would be good upgraded motors for the rockslide RS10

[@Evilslayer73]

So more turns=more heat?

[@makestuffbetter19]

I’d love to know how many amps a 550 motor can handle based on the number of turns.

[@acerforge3882]

Wouldn't it be much more useful to represent the capability of each motor by graphing power output against rpm for a range of current values which are within the capability of the controller and battery? Using motor spindle torque doesn't represent torque at the wheels whereas the power output can be combined with wheel speed to give a representative torque figure. I'm suggesting that graphs of actual motor characteristics would be much easier to understand.

[@HolmesHobbies]

great idea!

[@ateaserc]

Your theoretical is sound, isolating variables to establish relationships to outcomes will be the hardest part you’ll face but keep digging.

[@EZCheezyBeef]

I don't think the numbers don't work out exactly the way you think they should for two reasons. First is that you should run your kelvin test at a number of different amperages to take an average result. Second test conditions were not the exactly the same for every motor (lead lengths and quality mostly). I try running the same test straight to the motors(no wires) and and take measurements at several different (running)loads.

[@Gibsonlife573]

Sometimes most silliest people are the smartest people on earth LOL I know homes like to be silly but he smart

[@HolmesHobbies]

thx Gibson!

[@tomjones5860]

I think we'd need to know proper wheel speed and wheel torque required to move a vehicle over an obstacle. Then find the gear ratio to match each motor's rpm sweet spot to that wheel speed. 15,000rpm motor obviously needs different ratios than 30,000rpm motor. Then determine the amp draw needed to produce the torque. 30,000rpm motor with twice the ratio will need half the motor torque of 15,000rpm motor to produce same wheel torque. If we're not willing to invent a new gearbox then throw out all turn motors that don't fit common existing ratios. I have a feeling 4t motor, or whatever crazy low turn, will provide the best outcome but no gear reduction available. And of course, low turn motors require more expensive ESC. I also thought low speed motor control would be less relevant if motor is spinning twice as fast... 30,000rpm motor crawl speed would be twice the rpm as 15,000rpm motor at the same crawl speed because gear ratio are double. But heck I don't know. Its just intuition but so many things are counterintuitive.

[@TRKISH324]

I really smoked the wrong sh*t before watching this.

[@middleway1885]

Boop

[@nikolajc7617]

Thats a lot we dont need to know just to get watch hours.

[@HolmesHobbies]

@nikolajc7617 A snail can sleep for three years

[@FerociousSniper]

​@@HolmesHobbies so can I.

[@bufordgaston6713]

careful. I ran a holmes motor on a stock truck. it burned up in five minutes, and they said that I should have done a gear reduction for that motor, so it wasn't covered.

[@kjflyte5088]

I don't use brushed anymore, not very efficient to trail with . Brushless rules..

[@douglaselliott8298]

I'm very appreciative of this video. I've been near ready to trash this hobby thanks to every KZbin RC 'influencer' trying to conjole RC enthusiasts into unnecessary and stupidly expensive brushless motors and electronics for their 1/10 scale crawlers that are already doing 100+ scale MPH with the trigger fully pulled.

[@JimmyB55]

😅 every 1:1 crawler has 10,000 hp doesn't it?

[@thercvanman2730]

I'm not that good at math but 12mph is 120mph in the 1/10 world right 😂🤣

[@scottoblander9419]

@@thercvanman2730 I think its the square root of the scale times the speed. SO for 1/10th it would be 3.16 times the actual speed.

[@bsfunk44]

You know you don't have to do what the internet tells you to...right?..

[@bsfunk44]

John, you are such a super genius that you immediately lose some of us in the first couple minutes of every vid🤣🤣🤣. Eat some paint chips and sleep under some power lines for a few weeks before you post up the next video😁.